odd shudder

[gwoods]

I am almost at 71k miles.

I noticed coming home today that when driving under 40mph after coasting when I gently press the gas pedal the car shudders almost like its starved for fuel? If I nail it no shudder it just goes?

Also taking off from a stop I feel a shudder at about 1000 rpm and then the car goes? It almost feels like drive train slop?

I have an idea what is going on but wanted some input from the board

[zozoka1212]

Torque converter is my guess.

[BrandAidDesignG35]

I have noticed some shudder @ 60mph in 5th gear while coasting downhill or gentle slope.

I also interestingly use a Fujita setup, I know we're on different motors, but the similar symptoms have me Do you happen to have an engine damper installed? I noticed the shudder prominently for the first time - especially after I installed the torque damper... I was on a quick drive to test and then cruising along down hill and it shook the car violently.

I can avoid this altogether by cruising a bit faster, or like you mentioned just gas it lightly and it's gone.

[gwoods]

Torque converter is my guess.

That is what I think it is too. It does it in reverse as well but it feels worse in reverse.

I have had the dealership service the transmission 3 times in 71k miles the most recent service was about 2 weeks ago at 69600 miles.

I checked the dipstick today after driving about 23 miles to work on a level road with the car in park and e brake on. It is over filled as far as I can tell. Would overfilling the transmission make it feel like the torque converter is failing?

Shudder in drive you can see the tach drop but my foot is still on the peddal



Shudder in reverse you can see the tach drop



Full throttle run to 60 from this morning

Dipstick looks like its over filled. I wiped it and dipped it 3 times it is up in the wavy parts.

[gwoods]

I have noticed some shudder @ 60mph in 5th gear while coasting downhill or gentle slope.

I also interestingly use a Fujita setup, I know we're on different motors, but the similar symptoms have me Do you happen to have an engine damper installed? I noticed the shudder prominently for the first time - especially after I installed the torque damper... I was on a quick drive to test and then cruising along down hill and it shook the car violently.

I can avoid this altogether by cruising a bit faster, or like you mentioned just gas it lightly and it's gone.

I just have the Fujita kit and drilled slotted brake rotors with ceramic pads. Otherwise the car is bone stock... oh and bigger tires.

If I don't just use very light throttle the shudder doesn't present itself. The way I drive is accelerate then coast up to the traffic in front of me. Then light acceleration then coast. It gets me 19-21 mpg even with my stop light full throttle runs through 3rd and hitting 100MPH + about twice a day when the road is 6 lanes and open.

[gwoods]

There is a junk yard about 8 miles from my house with a 07 G35 Sedan total with 16k miles on it they want $1000 for the transmission. I think when/if it fails I'm going to swap in a junk yard transmission then rebuild mine and keep it in a plastic sleeping bag for later.

[BrandAidDesignG35]

Would installing my engine damper affect the torque converter? What is the function of the torque converter, and would a transmission flush help with this issue???

[BrandAidDesignG35]

There is a junk yard about 8 miles from my house with a 07 G35 Sedan total with 16k miles on it they want $1000 for the transmission. I think when/if it fails I'm going to swap in a junk yard transmission then rebuild mine and keep it in a plastic sleeping bag for later.

That sounds like a good deal, it's going to be hard to find parts (salvage) for G35s, I've had little luck around here

[gwoods]

Would installing my engine damper affect the torque converter? What is the function of the torque converter, and would a transmission flush help with this issue???

http://en.wakopedia.org/wiki/Torque_converter

Its pretty much the clutch for the automatic transmission.

Stock stall on a G is around 1000,1100 rpm which is what makes me think my issue is a torque converter issue.

In my Hemi Ram I had a Suncoast 2800 stall torque converter with an organic clutch plate, the housing was billet steel. It multiplied torque by 2.54 whereas the stock converter was 1.9 torque multiplication it was AWESOME!!!

Suncoast

Stock

In Racing a high stall torque converter lets you put your foot on the gas and on the brake and raise the rpm's up to the stall so you can launch at a higher RPM. In your G if you put your foot on the brake and gas the car is going to start moving at about 1000-1200 rpm. In my hemi ram with this converter I would hold the brake and gas until 2800 rpm before launching.

Video of 2800 rpm stall launch at the track. Listen to it fall on its face in 3rd :-(

[zozoka1212]

Jeff that's your torque converter. But there is a slightly chance you might be good with ECU update. I know it sounds funky but Sometimes the torque converter acting weird because of the signal from the ECU. Not sure if your car is up to date with softwares but there is a new update on the ECU. Be carefull with the 07 and 08 transmission. For some reason Infiniti keeps the 2 in diffeent file. They have different updates.

The 07 has the latest 2371-JK69D and the 08 has the latest 23710-1NA8C. Really not sure why there is a diferent software for the 2 if they are the same. Probably Poyzi knows better.

There are not many companies making torque converters and where Nissan is geting them and what type of converter they use in our car.

Would installing my engine damper affect the torque converter? What is the function of the torque converter, and would a transmission flush help with this issue???

The torque converter basically does the same thing for the Auto transmission what the clutch does for the Manual. There are a little more to it but the basic is the same. With the manuall you basically controll the clutch with your foot. Like when you fathering, dump it etc, However the auto transmission has to do it on its own and got signals from the ECU/TCU. Car companies with all these modern learning ECU/TCU systems they not making it easier to themself. I am not a big fan of learning ECU I rather have few different maps and have a switch to chose what my driving style would be for the next few minutes. Not let something pick for me thinking I will be driving hard since i was driving it hard for few hours before. As you know I am not an expert so could be wrong.

[zozoka1212]

EDit Jeff just beat me to it.

I am capitain slow. LOL

[BrandAidDesignG35]

Video of 2800 rpm stall launch at the track. Listen to it fall on its face in 3rd :-(

What happened? It sounds like you hit the brakes after you crossed the line?!? Was that when you blew the transmission?

And thanks for the info guys, I know my G35 was shuddering at around exactly 2100 rpm... so perhaps I'm looking at something else? I am going to check my air fiter as it may be dirty, check my plugs, and maybe remove the torque damper to see if this helps...

Really I'm not worried because it only happens to me every month or so maybe Right now I have to get a bunch of stuff for the G...

4 new winter tires2 compression rods

[gwoods]

What happened? It sounds like you hit the brakes after you crossed the line?!? Was that when you blew the transmission?

I blew the transmission on I-10 almost at baseline street racing a Celica GT with extra rice.

I had 5 different exhaust systems on the truck trying to find max power. They system in this video made great power in the lower RPM's but really killed the torque in the upper RPM's, when the truck shifted into 3rd it did not have enough power to pull third gear, around 75-80mph. I love how fast this exhaust system was in 1st & 2nd gear though!

[gwoods]

Jeff that's your torque converter. But there is a slightly chance you might be good with ECU update. I know it sounds funky but Sometimes the torque converter acting weird because of the signal from the ECU. Not sure if your car is up to date with softwares but there is a new update on the ECU. Be carefull with the 07 and 08 transmission. For some reason Infiniti keeps the 2 in diffeent file. They have different updates.

The 07 has the latest 2371-JK69D and the 08 has the latest 23710-1NA8C. Really not sure why there is a diferent software for the 2 if they are the same. Probably Poyzi knows better..

That is VERY interesting! I received a new ECU at 69k miles about 2 weeks ago. I am thinking you may have solved my problem.

[zozoka1212]

Sometimes I get it right. LOL

[suby01]

i was just going over this thread and YES ZOZO!!!!

woods thats your problemo, is your ECU not ur transmission or TQC. get the update from the dealer also try just for ha ha s doing a ecu reset see if that changes anything.

[gwoods]

ECU has been reset.Dealership kept the car for a day and put 30 miles on it trying to duplicate

The stumble/studder is still there. If it were mechanical it should have started getting more frequent/violent. It is the same so it must be electrical.

I'm guessing MAF's are dirty.

Started a new thread about cleaning MAF's